Trench storage dynamic random access memory cell with vertical transfer device

Abstract

A trench storage dynamic random access memory cell with vertical transfer device can be formed in a wafer having prepared shallow trench isolation. Vertical transfer device is built as the deep trenches are formed. Using square printing to form shallow trench isolation and deep trenches, allows for scaling of the cell to very small dimensions.

Description

1. Field of the InventionThe present invention generally relates to integrated circuit dynamic random access memories, and more particularly to trench capacitor construction.2. Background DescriptionAs dynamic random access memory (DRAM) cells are scaled to meet chip-size requirements for future generations, the channel length of transfer devices on the surface of the silicon substrate can no longer be scaled without degrading subthreshold leakage requirements (or retention time requirements). Process steps become complex and incompatible with standard DRAM processes, when vertical transfer devices in the DRAM cell are employed to decouple the channel length from layout ground rules.It is therefore an object of the present invention to provide a vertical transfer device which is built on top of a deep trench storage node and is compatible with contemporary DRAM process steps.By integrating a robust transfer device in a Dynamic Random Access Memory (DRAM) cell having a shallow trench...

AI Technical Summary

Problems solved by technology

As dynamic random access memory (DRAM) cells are scaled to meet chip-size requirements for future generations, the channel length of transfer devices on the surface of the silicon substrate can no longer be scaled without degrading subthreshold leakage requirements (or retention time requirements).

Process steps become complex and incompatible with standard DRAM processes, when vertical transfer devices in the DRAM cell are employed to decouple the channel length from layout ground rules.

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